Here is Active Autowerke's exhaust for the new F20 328i with the turbocharged N20 four-cylinder. The pictures you see below are of the prototype version but the production version should not differ by much and is currently under construction and should be available in two months time. The exhaust alone provides gains of 9 horsepower at the wheels and 13 pound-feet of torque at the wheels as measured on the Active Autowerke Mustang Dyno.

Very nice gains for what is a rear section exhaust. Intro pricing is a very reasonable $599 so F30 328i owners should jump on this early on if considering an exhaust. Pictures, dyno, and sound clip below.